Quick acting circuit breaker



Aug. 4, 1970 A. TREPTOW HAL 3,522,565

QUICK ACTING CIRCUIT BREAKER Filed March 29, 1968 Inventors; Arno Tre i-ow 0H0 WM BY WALK? United States Patent Int. Cl. H6111 9/20 US. Cl. 335-170 6 Claims ABSTRACT OF THE DISCLOSURE A circuit breaker having an electromagnetic tripping mechanism for automatically opening the circuit breaker in case of an overload current. When the armature of the tripping mechanism is attracted by the core due to the flow of an overload current, the following occurs: first, a latching device between the movable contact arm of the circuit breaker and the positioning means for that arm is released and the contact arms are separated. The movable contact arm is then abruptly struck, after which the tripping means are uncoupled from the movable contact arm. The tripping means are adjustable so that the circuit breaker can be set to open at any desired overload current.

BACKGROUND OF THE INVENTION The present invention relates to a self-tripping breaker for use in direct current systems, which circuit breaker incorporates a contact arrangement wherein there appear electrodynamic forces that are a function of the current and wherein an electromagnetic tripping mechanism is provided which acts on the movable contact arm of the circuit breaker, this movable contact is being latched to other switch actuating parts independently of the tripping mechanism.

There exist circuit breakers, particularly those suitable for use in polyphase systems, wherein an armature of an electromagnetic tripping mechanism acts on the movable contact arm either directly or through an intermediate element, so as quickly to separate the contacts in the event of a short circuit or other overload. At the same time, the switching parts are unlatched so that the circuit breaker can once more assume its starting position.

There also exist electric circuit breakers in which the movement that separates the contacts is assisted by the electrodynamic forces.

In still other circuit breakers, there is, in addition to the coupling of the tripping mechanism, a latching arrangement between the positioning element and the movable contact arm. After the contacts have been separated, the parts are unlatched so that the movable contact arm can return to its starting position independently of the uncoupling of the tripping mechanism. If, however, the contacts are to be opened against the force of the contact spring, it is difiicult if not impossible to adjust the circuit breaker so as to make it respond to relatively small overload currents.

SUMMARY OF THE INVENTION It is, therefore, the primary object of the present invention to improve heretofore known circuit breakers so as to make it possible to use such circuit breakers in direct current circuits and to make it possible to adjust the circuit breakers so that they will be tripped already at small overload currents.

In accordance with the present invention, the above objects are achieved by equipping the circuit breaker with an electromagnetic tripping mechanism in which, upon attraction of the armature of the tripping mechanism by the core due to the flow of an overload current, the following occurs: rirst, the latching means between the movable contact arm and the positioning means for that arm are released and the contact arms are separated. The movable contact arm is then abruptly struck, after which the tripping means are uncoupled from the movable contact arm.

In the preferred embodiment, the tripping means are adjustable so that the circuit breaker can be set to open at any desired overload current.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, the same shows a circuit breaker having a stationary contact arm 1 and a movable contact arm 2, the same carrying contact elements 3 and 4, respectively, which engage each other so as to form an electrical contact. The movable contact arm 2 is carried by a movable carrier arm 6, the contact arm 2 being pivotal with respect to the carrier arm 6 about a pivot axis 5. The carrier arm 6, in turn, is mounted for pivotal movement about a fixed pivot axis 7, so that the contact arm 2 and the carrier arm 6 are connected in an overhung manner, i.e., in a manner that the connection 5 between these two arms itself moves. The contact arm 2 is latched, at 8, by a pressure spring 34 which pushes a roller element 35 against a notch portion 36 of a cam surface 37 which is rigidly fixed to the contact element 4. This type of mechanism is disclosed in Pat. No. 3,238,339 issued Mar. 1, 1966, and common ownership with the present application. The end of pressure spring 34 opposite roller 35 acts against a positioning element 9, the latter being held in position by a switch lock 25 which is disposed between position element 9 and an actuating handle 26. Switch lock 25 is released by movement of armature 14 as is indicated schematically by dotted line 27. The arrangement of a switch lock between an actuating member and a setting member as well as its connection with a trigger is used in many switches and is conventional in the switch art. The lower end of the carrier arm 6 extends, pin-like, into an elongated slot 11 of a further arm 12 which is pivotally mounted at 13, on the armature 14 of an electromagnetic tripping mechanism 15. The core 16 of the tripping mechanism 15 is arranged in the sphere of influence of the current flowing through the circuit breaker, for example on the current lead-in 17 which is connected, via a flexible connection shown fragmentarily at 18, with the movable contact arm 2. The armature arm 12 is connected to the armature 14 via a draw-bar 19 which is secured, by means of screws 20, to the armature 14, the arrangement of the parts being such that the position of the arm 12 can be varied with respect to the armature 14; this, in turn, adjusts the width of an air gap 21 so that the tripping mechanism can be set to respond, i.e., to trip, at different overload currents. The position of the parts, and thus the current to which the tripping mechanism is set to respond, can be read oif an indicating device 22. The armature 14 is held in its open, i.e., unattracted, position by means of a spring 23. At this time spring 34 presses contact pieces 3 and 4 together so that dependable current transfer occurs.

Assuming now that the current through the circuit breaker becomes excessive overload current, e.g., if the current is that resulting from a short-circuit current, the

amature 14 is attracted by the magnetic core 16. Armature arm 12 pivots in a counterclockwise direction. This movement commences the release of the switch lock 25 for the positioning element '9. The switch contacts 3 and 4 remain in engagement with each other, however, for a finite period of time under the pressure of spring 34. However, continued movement of armature 14 causes continued rotation of the carrier arm 6 and eventually its free end 24 strikes the movable contact arm 2. The contacts 3 and 4 then move very quickly away from each other. At first, the cam notch 36 may push against roller 35 to slightly compress the spring, but the roller soon falls into the position shown in FIG. 2. Accordingly, the circuit breaking action occurs in a lesser period of time than would be required if the contacts had to be separated either by armature 14, or by reliance upon the switch lock 25 and the latch release mechanism 27. After a short period of time, positioning element 9 moves to the right as shown in FIG. 3 and roller element 35 again engages notch 36 and the parts are ready to be set when desired for the next switching action. As the switching mechanism goes back into its starting position, the latched engagement between the movable contact arm 2 and the positioning element 9 is reestablished, so that the circuit breaker is once more ready to be closed (FIG. 3).

It will thus be seen that, in accordance with the present invention, there is provided a circuit breaker which is equipped with electromagnetic tripping means which, upon the attraction of the armature 14 by the core 16 due to the flow of an overload current, operate so as to first release the latching device 8 and to separate the contact arms 1 and 2. The movable contact arm is abruptly struckthis being done by the free end 24 of the carrier arm 6-and the tripping means are then uncoupled from the movable contact arm.

The fact that the air gap 21 can be adjusted by means of the draw-bar 19 is particularly advantageous because the adjustment of the air gap does not change the pivotal movement of the carrier arm 6 which is required to break the engagement 8 and to separate the contact elements 3 and 4.

It will be understood that the above description of the present invention is susceptible to various modifications, changes, and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

What is claimed is:

1. A circuit breaker comprising, in combination:

(a) a stationary contact arm;

(b) a movable contact arm mounted for movement With respect to said stationary contact arm;

() positioning means for positioning said movable contact arm;

(d) latching means interconnecting said movable contact arm and said positioning means; and

(e) electromagnetic tripping means comprising:

(1) a core arranged in the sphere of influence of current flowing through the circuit breaker,

(2) an armature arranged for movement with respect to said core, and

(3) means, operative upon attraction of said armature by said core due to the flow of an overload current, for first releasing said latching means and separating said contact arms, for thereafter abruptly striking said movable contact arm, and for thereafter uncoupling said tripping means from said movable contact arm, said means comprising an armature arm carried by said armature, a carrier arm coupled directly to said armature arm, said carrier arm and said movable contact arm being connected together for movement wherein the connection between said movable contact arm and said carrier arm itself moves.

2. A circuit breaker as defined in claim 1 wherein said means (3) further comprise means for adjusting the position of said armature arm relative to said armature, thereby to allow the air gap between said armature and said core to be adjusted.

3. A circuit breaker as defined in claim 2 wherein said adjusting means comprise a draw-bar.

4. A circuit breaker as defined in claim 2 wherein said means (3) further comprise means for indicating the position of said adjusting means, and hence the current at which said tripping means become operative.

5. A circuit breaker as defined in claim 1 wherein said carrier arm is coupled at one end thereof to said armature arm, and wherein the other end of said carrier arm is arranged to abuptly strike said movable contact arm.

6. A circuit breaker as defined in claim 5 wherein the coupling between said armature arm and said carrier arm is a pin and elongated slot-type coupling.

References Cited UNITED STATES PATENTS 3,238,339 3/1966 Fehling -1 335l6 FOREIGN PATENTS 165,563 7/ 1921 Great Britain. 558,333 8/1955 Italy. 1,158,869 6/1958 France.

BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner 

